The present invention relates to an air turbine driven environmental control system for an aircraft.
Aircraft power systems are comprised of several major subcomponents such as the engine, the environmental control system, anti-icing systems, and thermal management systems. Typically, these subsystems are designed relatively independently of one another with power being transferred from one subsystem to another in certain predefined ways.
The purpose of an aircraft environmental control system is to supply cooled pressurized air to the cabin and flight deck. This is typically accomplished by the use of an air cycle machine. FIG. 1 illustrates a typical environmental control system 10 for an aircraft. Depending upon the mission point, bleed air from the engine 12 is removed from either the mid- or high-pressure stages of the high compressor 14. The bleed air is first cooled by ram air in a primary heat exchanger. The bleed air is then further compressed in the compressor section 16 of the air cycle machine. Additional cooling of the bleed air is performed in a secondary heat exchanger 18 again using ram air as the coolant. The bleed air is then expanded to the desired pressure across the turbine section 20 of the air cycle machine. The expansion process produces the necessary work required to drive the compressor 16 via shaft 22 and significantly drops the temperature of the bleed air. The cooled bleed air exiting the turbine section 20 is mixed with cabin recirculation air to maintain the temperature of the air entering the cabin at a given level.
One of the deficiencies of this type of system is the penalties which it creates with respect to engine losses. The engine bleed air used for this system could be as much as 5% of the core flow from the engine. Other deficiencies include the weight which is added as a result of having to provide one or more heat exchangers. Still further, the system does not address the issue of providing power to or thermally managing other aircraft components.
Accordingly, it is an object of the present invention to provide an improved environmental control system for an aircraft.
It is a further object of the present invention to provide an environmental control system as above which also provides power to other aircraft components.
The foregoing objects are attained by the environmental control system of the present invention.
In accordance with the present invention, an improved environmental control system is disclosed. The environmental control system broadly comprises means for using bleed air from an engine to provide power to an aircraft mounted accessory drive and to provide improved anti-icing capabilities and means for supplying cooled pressurized ram air to the aircraft flight deck and cabin. The environmental control system in a preferred embodiment has a first subsystem for providing power to an aircraft mounted accessory drive and a second subsystem for supplying pressurized ram air at a desired temperature to at least one of a flight deck and a cabin. The second subsystem includes a vapor compression cycle loop for removing energy from the ram air prior to the ram air being supplied to the at least one of said flight deck and said cabin.
Further, in accordance with the present invention, a method for controlling the environment of an aircraft is provided. The method broadly comprises the steps of providing power from an engine onboard the aircraft to an aircraft mounted accessory drive, supplying pressurized ram air at a desired temperature to at least one of a flight deck and a cabin, providing a vapor compression cycle loop, and removing energy from the ram air using the vapor compression cycle loop prior to supplying the ram air to the at least one of the flight deck and the cabin.